This invention relates to marine vessels.
EP-A-0 495 722 discloses a marine vessel comprising a central hull stabilised by first and second pairs of outboard sponsons and propelled by propulsion means carried by the sponsons or the hull, the first pair of sponsons being disposed forwardly of the second pair of sponsons, the sponsons of the first pair being disposed at a higher level than the sponsons of the second pair, so that, at zero heel angle, at the load water line of the vessel, the sponsons of the second pair are in contact with the water while the sponsons of the first pair are disposed above the water.
The present invention relates to such a marine vessel, characterised however in that, at zero heel angle, the waterline breadth of each sponson of the second pair of sponsons is greater than the draft thereof, and that should the vessel heel to one side, the sponson of the second pair on the downgoing side of the vessel dips deeper into the water, while the other sponson of the second pair which is on the upgoing side of the vessel emerges from contact with the water, and the sponson of the first pair on the downgoing side of the vessel is simultaneously brought into contact with the water, so as to stabilise the vessel.
The hull may have a waterline length to beam ratio greater than 6 and preferably 10.
The vessel may be provided with first and second pairs of outboard sponsons, with the first pair disposed forwardly of the second pair, the sponsons of the first pair being disposed at a higher level than the sponsons of the second pair so that, at the load water line of the vessel, the sponsons of the second pair are in contact with the water while the sponsons of the first pair are disposed above the water whereby, should the vessel heel to one side, the sponson of the first pair on the heeling side of the vessel is brought into contact with the water, so as to create an upwardly acting restoring force which tends to stabilise the vessel.
The sponsons of each pair of first and second sponsons may be spaced from each other longitudinally of the vessel.
The sponsons of each pair of first and second sponsons may be combined so as to form a single integral structure of stepped form.